Cadillac DeVille Engine Overheat & Air Flap Malfunction

Had similar issues with a 2006 Cadillac STS. The thermal management system showed multiple faults during a diagnostic scan. The main problem turned out to be a faulty flap motor in the air intake system, which prevented proper airflow management. Initially, the symptoms matched yours, persistent check engine light and engine overheating. The root cause was the air flaps getting stuck in a closed position, limiting crucial airflow to the engine. This is actually a serious issue that can lead to severe engine damage if left unattended. The repair required: Complete diagnostic scan to confirm the flap motor failure, Replacement of the air intake flap motor assembly, Recalibration of the thermal management system, Clearing all system fault codes After the repair, both the overheating and check engine light issues were resolved. Would recommend having a proper diagnostic scan done first, many shops misdiagnose this as a simple thermostat issue when its actually the air management system causing problems. Watch out for mechanics who only address the overheating symptoms without checking the air intake system. The flap motor issue is a known weak point in these models and requires specific diagnostic procedures.

I appreciate the detailed response on the air intake system issue. The description matches my problems exactly, especially the stuck flap motor causing the cooling system to malfunction. My check engine light finally went off after the repair, and the engine overheating issues are resolved. Could you share how much the complete fix cost you? Also, have you experienced any similar thermal management problems since the repair? Just want to make sure this is a long-term solution before I commit to the full repair at a shop.

After getting the active air flap system fixed at my mechanic, I have not experienced any thermal management issues. The diagnostic scan showed the electromechanism was defective, and replacing it solved both the check engine light and overheating problems. The total repair cost was 590€, which included the new flap motor and labor. This repair proved to be a permanent solution for my Cadillac STS. The engine now maintains proper temperature even during long drives, and the cooling system works perfectly. No warning lights have appeared since the fix, confirming that addressing the faulty flap motor was the right approach. The proper function of the active air flap makes a noticeable difference in engine temperature control. A functioning flap motor ensures optimal airflow management, preventing the overheating issues that were previously causing problems. Based on my experience, investing in the complete repair is worth it to prevent potential engine damage from chronic overheating.

Thanks to everyone who helped diagnose my Cadillac's issues. After taking it to a certified mechanic who specializes in cooling system problems, they confirmed the active air flap failure. The diagnostic scan revealed exactly what was mentioned, a faulty flap motor preventing proper airflow. The total repair came to 650€, which included: New flap motor assembly, System diagnostics, Labor costs, Coolant flush The mechanic completed everything in one day. Its been 3 weeks since the repair, and the engine temperature stays perfectly normal. No more check engine light, and the cooling system works exactly as it should. Really glad I asked here first, saved me from getting more incorrect fixes at other shops that would have just masked the symptoms without solving the air intake system problem.